Technical Field
This technology relates to integrated circuit memory technologies, including technologies using phase change materials and methods for manufacturing such devices.
Description of Related Art
Many three dimensional (3D) memory technologies using phase change material, and other programmable resistance materials have been proposed in order to make high density memory. For example, Li et al., “Evaluation of SiO2 Antifuse in a 3D-OTP Memory,” IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY, VOL. 4, NO. 3, SEPTEMBER 2004, describes a polysilicon diode and an anti-fuse arranged as a memory cell. Sasago et al., “Cross-point phase change memory with 4F2 cell size driven by low-contact-resistivity poly-Si diode,” 2009 Symposium on VLSI Technology Digest of Technical Papers, pages 24-25, describes a polysilicon diode and a phase change element arranged as a memory cell. Kau et al., “A stackable cross point phase change memory,” IEDM09-617, (2009) pages 27.1.1 to 27.1.4, describes a memory post including an ovonic threshold switch OTS as an access device with a phase change element. These technologies rely on a combination of an access device and a memory element to construct the memory cell.
For setting and resetting programmable resistance materials, thermal processes can be used in which heat is generated in an active region of the memory material to cause changes in resistance. For phase change materials, the change in resistance can be induced by causing a transition between a crystalline solid phase and an amorphous solid phase. The heat is typically produced by applying a current through the active region of the programmable resistance material. If the surroundings of the memory element dissipate the heat quickly, a larger amount of power is needed to compensate for the dissipated heat, and reach the temperatures needed. To achieve higher powers in these settings, higher current density is needed in the active region.
Therefore, it is desirable to provide a memory technology that is suitable for high density structures, and lower operating current.